The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
In a present day, standardized, AdvancedTCA telecommunications chassis a backplane is employed that separates a front card cage portion of the enclosure where front boards are located from a rear card cage area where Rear Transition Modules (RTMs) are located. Typically the front boards have components that produce significantly greater power dissipation than the RTMs, and thus require a significantly greater volume of air flow to sufficiently cool than the RTMs require for adequate cooling. Present day open specifications for an AdvancedTCA chassis state that the power dissipation of an RTM is to be about 0.125 of that of a front board. However, present day cooling subsystems used with an AdvancedTCA chassis are set up in terms of the total area of the RTMs versus that of the front boards. The area of an RTM is about 25% that of a front board. So a typical present day cooling system will be set up such that the RTM card cage area of a chassis (i.e., enclosure) will receive about 25% of the total volume of air flow being delivered to the chassis. This is so even though the power dissipation target for each RTM is stated to be only 0.125% of the front board power dissipation.
The actual needed cooling air flow through an RTM card slot is directly proportional to the power being dissipated by an RTM, and thus is independent of the actual printed circuit board (PCB) area of the RTM. However, as described above, with a typical chassis cooling subsystem design, the RTMs will each be receiving an air flow that is proportional to its PCB area. This leads to substantially higher air flow to the RTMs than what is actually needed to adequately cool the RTMs, which in turn leads to inefficient use of the cooling air flow being directed through a chassis. In fact, the air flow over each RTM in an AdvancedTCA chassis may actually be about double that which is needed to effect adequate cooling of the RTM. This unnecessarily high air flow over the RTMs also increases the overall system energy consumption and contributes to increased acoustic noise emissions from the air flow flowing through the RTM card cage.